The industrial mint crops are widely cultivated for the commercial production of essential oils. Mint family species (Mentha spp. L.), including peppermint and spearmint, are important specialty crops valued for the essential oils produced in trichomes on the surface of leaves. Spearmint is particularly known as a major source of carvone-rich essential oil for perfumery and flavoring industries and is grown worldwide. Spearmint is a fast-growing perennial crop capable of biosynthesizing significant amounts of essential oils containing a variety of ingredients, such as rosmarinic acid and other phenolics. For example, the essential oil of Mentha arvensis Linn. var Piperascens is a well-known source of the monoterpene ‘menthol’ used in the cosmetics, pharmaceutical, food, confectionery and liquor industries.
Different varieties of a given plant species may provide different ratios of ingredients within the essential oils they produce. Different mint plant species and even different varieties of the same mint plant species provide different essential oil compositions that may vary widely. However, once a particular mint plant variety is identified, the plant may be clonally propagated and used to produce essential oils of a consistent content profile for a sustained period over at least several harvests.
Mint plants are capable of producing underground rhizomes which can be used as propagates for field planting. Mint plants are also capable of rapidly producing rooted branches which can aid in faster propagations. In addition, mint plants are typically easy to cultivate, can sustain several harvests annually, and exhibit rapid re-growth after each harvest, making mint plants amenable to methods of producing essential oils of a consistent composition on an industrial scale.